We’ve all the term before: Lower parts kit. LPK. Just “parts kit”. What is it, exactly? It’s super-important when it comes to building an AR 15. Although the stripped lower is technically considered the firearm of the thing, it’s the lower parts kit that makes it all work. Let’s break down exactly what’s in a lower parts kit, what each part is and what it does, and how it all works. Fire Control Group When most folks ask, “how does an AR 15 lower parts kit work?” They’re referring to the fire control group – all the other stuff in...